A variety of orthopedic casting materials useful in the immobilization of broken or injured limbs are known in the art. Among the first materials developed for this purpose were plaster of Paris bandages, which provided good moldability and palpability of fine bone structure, but which suffered from a number of disadvantages, including a low strength-to-weight ratio and slow strength build-up. Casting materials were later developed that addressed the problems associated with plaster of Paris bandages. For example, knitted fiberglass fabrics coated with water curable polyisocyanate prepolymer resins were developed which provided higher strength-to-weight ratios and improved air permeability. These materials, however, are not as compressible as plaster, tend to mask fine bone structure as the cast is applied, and are expensive to make.
Efforts continue in the art to provide orthopedic casting materials having good moldability, good palpability of fine bone structure, good extensibility, and fast strength build-up during application, and also having good strength-to-weight ratios and good air permeability after curing.